Most conventional pet doors generally include inner and exterior frames designed to be installed in a standard door or other structural unit of similar thickness. The thickness of standard interior and exterior doors is generally between 31.8 mm (1.25 in) and mm 57.1 mm (2.25 in) with 34.9 mm (1.375 in) and 44.4 mm (1.75 in) being most common for interior and exterior doors, respectively. The installation is intended to involve only cutting an opening in the standard door and securing the inner and exterior frames around the opening. Most conventional pet doors are designed to accommodate different thicknesses within the limited range of thicknesses found in standard doors. With few exceptions, they are not designed for installation into a structural feature with a thickness larger than approximately 76.2 mm (3 in), such as a wall. A basic exterior wall of a structure often has thickness of 152.4 mm (6 in) or more. When installing a conventional pet door into a wall, the options are limited.
One option is simply to install the inner and exterior frames around the opening and leave an unenclosed passageway through the interior of the wall between the inner and exterior frames. This option is generally unacceptable as the pet door then provides access to objects normally enclosed in the wall, such as the ends of construction fasteners (e.g., nails, screws), insulation materials, wiring, and plumbing. In addition, this option does not offer a particularly good environmental seal. Moreover, once outside the limited range of thicknesses found in standard doors, complications arise when trying to install a conventional pet door in structures having a thickness greater than that for which the pet door was designed and/or when trying to facilitate standardized installation in structural features having a wide range variance in thicknesses.
Another option is to build a custom tunnel through the wall using standard building materials. This significantly increases the skill and tools needed and the time, effort, and expense involved in installing the pet door. It is with respect to these and other considerations that the present invention has been made.